Liquid crystalline polyester resin has excellent heat resistance, flowability, electrical properties, and the like, and, utilizing such excellent properties, it has been increasingly demanded mainly in miniature precision molded articles for electric and electronic use. Further, in recent years, attention has been paid to its thermal stability and high thermal dimensional accuracy, and studies have been conducted for using in a liquid crystal display-supporting substrate in office automation equipment or cellular phones as a supporting substrate in heat-generating parts, structural parts of a lamp, and the like.
As a raw material of liquid crystalline polyester resin, p-hydroxybenzoic acid and 6-hydroxy-2-naphthoic acid as principal components; and diols such as hydroquinone, 4,4′-dihydroxybiphenyl, 2,6-naphthalene diol and aliphatic diol, dicarboxylic acids such as terephthalic acid, isophthalic acid, 2,6-naphthalene dicarboxylic acid, and aliphatic dicarboxylic acid, and amino group-containing monomers such as p-aminobenzoic acid and aminophenol as copolymer components are used.
Improving melt processability and preventing gas generation and bulging of a molded article by providing a specific composition ratio using, in particular, hydroquinone have been studied (Patent Documents 1 to 3).
In addition, prolonging a washing cycle of a reaction vessel by defining the temperature of an area located at the liquid level of a reaction solution and near the liquid level of the reaction solution thereabove and returning distillate by blowing has been studied (Patent Document 4). Further, obtaining a liquid crystalline polyester resin having excellent heat resistance by distilling a defined amount of acetic acid in an acetylation reaction vessel and then transferring a reaction solution to a polymerization vessel has been studied (Patent Document 5).
Meanwhile, for producing a liquid crystalline polyester resin, there is an acetylation reaction process using acetic anhydride. In the acetylation reaction process, a vapor phase portion of a reaction vessel and pipes at even upper parts corrode, and, accordingly, countermeasures therefor have been studied. For example, a method of preventing corrosion of an acetylation reaction vessel and at the same time improving color tone and processability by selecting glass lining, titanium, or hastelloy as a material of the reaction vessel has been proposed (Patent Documents 6 to 9).